This invention relates generally to lift mechanisms and, more particularly, to a stairway wheelchair lift operable to transport a handicapped person in ascending and descending directions along a stairway.
The increasing public awareness of the rights and needs of handicapped individuals has led to various improvements which provide handicapped persons, and, in particular, those confined to a wheelchair, with access to formerly inaccessible locations. Although horizontal movement by handicapped persons has been greatly facilitated by the widespread use of sidewalk, entrance way and curb ramps, and the like, vertical movement, and in Particular, vertical travel between the floors of a multi-story building, has long been a formidable obstacle.
In larger multi-story structures, such as those having four or more stories, elevators provide a popular and convenient form of transportation between floors. Such elevators, provided they are accessible to and easily operated by handicapped persons, offer a convenient means for transporting handicapped persons between floors.
In smaller multi-story structures, however, where, for various reasons, such as cost and/or architectural limitations, the installation of an elevator system is impractical, some other system must be provided to permit handicapped persons access to all floors. As a rule, such smaller structures include one or more stairways between floors, and one known approach has been to provide a stairway lift mechanism installable along an existing stairway and operable to transport a wheelchair-bound person, between floors along the stairway.
To be effective, a stairway lift mechanism must be safe, reliable and easily operated by persons whose movement is often severely limited. As stairway lift mechanisms typically move along the same stairway used by other, non-handicapped people, it is also desirable that such mechanisms avoid, to the extent possible, interference with general use of the stairway both when a passenger is being transported and when the mechanism is standing idle. Furthermore, because stairways can differ considerably from one structure to the next, it is often necessary to adapt a stairway lift mechanism for installation in a particular stairway on a more or less custom basis. Accordingly, a stairway lift system which can be readily and economically adapted for use in various particular stairways regardless of the physical constraints thereby imposed, will not only provide significant economic benefits, but will also encourage more widespread use of the system and, thus, confer a corresponding benefit on the handicapped population.
In view of the foregoing, it is a general object of the present invention to provide a new and improved stairway wheelchair lift.
It is a more specific object of the Present invention to provide a new and improved wheelchair lift which is safe and reliable, and which can be easily operated by a handicapped person.
It is still a further object of the present invention to provide a stairway lift which can be readily and economically adapted for use with particular stairways.
The invention provides a lift mechanism for transporting a passenger between first and second vertically displaced locations separated by stairs. The lift mechanism comprises a rail extending along the stairs and a drive chain movable within the rail. A motor drive unit is adapted to operatively drive the chain, and a movable passenger lift platform is coupled to the chain and is adapted to ride along the rail in response to driving movement of the chain. A position sensor is included for sensing the position of the lift platform, and a control, responsive to the sensor, is provided for controlling the movement of the platform in accordance with the position of the platform along the stairway.
The invention also provides a stairway wheelchair lift comprising a substantially planar vertical housing which has a lower and an upper end, and which is adapted to be supported for movement along a rail. The lift further includes a generally planar platform, having a load supporting surface, pivotally joined adjacent the lower end of the vertical housing for movement between a raised position, wherein the platform is substantially parallel to the vertical housing, and a lowered position, wherein the platform extends substantially perpendicularly outwardly from the vertical housing. A first elongate guard arm is coupled to the vertical housing adjacent the upper end and is movable between a raised position, wherein the first arm extends upwardly from the vertical housing, and a lowered position, wherein the arm extends substantially perpendicularly outwardly from the vertical housing. A second elongate guard arm is coupled to the vertical housing adjacent the upper end and is movable between a raised position, wherein the second arm extends upwardly from the vertical housing and a lowered Position wherein the second arm extends substantially perpendicularly outwardly from the vertical housing.
The invention also provides a chain comprising a first metallic chain link having opposite ends, at least one of which ends is coated with a nonmetallic coating, and a second metallic chain link having opposite ends, at least one of which ends interlocks with the coated end of the first link such that metal to metal contact between the interlocking ends is substantially avoided. A first generally spherical rigid member is molded onto the first link and surrounds a portion of the first link between the opposite ends of said first link. A second generally spherical rigid member is molded onto the second link and surrounds a portion of the second link between the opposite ends of the second link. In one embodiment, each of the spherical rigid members includes a pair of side-by-side notches for receiving an externally applied driving force.
The invention also provides a motor drive unit for powering a drive chain. The motor drive unit comprises a frame, a gear box supported by the frame, and a sprocket carried by the gear box. The sprocket is adapted to support and drive the drive chain, and a tensioning mechanism is provided for adjusting the position of the gear box with respect to the frame to provide adjustment of tension of the drive chain.
The invention also provides a drive sprocket adapted to be mounted on a rotatable shaft and operable to drive a chain of the type having a plurality of interlocking links and a drive member, having a pair of side-by-side notches, molded around each of the links. The drive sprocket comprises a first side plate which is adapted to be mounted on the rotatable shaft and has an outer periphery adapted to engage one of the side-by-side notches in each of a plurality of the drive members. The drive sprocket further comprises a second side plate which is adapted to be mounted on the rotatable shaft and which includes an outer periphery adapted to engage the other of the side-by-side notches in each of the plurality of drive members.
The invention also provides a carrier for supporting a passenger lift platform for movement along the rail assembly of a passenger stairway lift mechanism wherein a drive chain is housed within the rail assembly. The carrier comprises a platform support bracket for supporting the passenger lift platform, a coupling mechanism for coupling the Platform support bracket to the chain within the rail assembly, and a pair of opposed brake members housed within the rail assembly adjacent the coupling mechanism. The carrier further comprises a wedge member coupled to the platform support bracket and drivable between the opposed brake members to bias the brake members outwardly into engagement with the rail assembly. The wedge member is movable between an extended position, wherein the brake members are biased outwardly into engagement with the rail assembly with sufficient force to substantially prevent movement of the platform support bracket, and a retracted position wherein the brake members do not engage the rail assembly with sufficient force to substantially prevent movement of the platform support bracket. The carrier also includes a brake control mechanism responsive to a control input for causing the wedge member to move from the retracted Position to the extended position in response to the control input whereby movement of the platform support bracket is substantially prevented following response of the brake control mechanism to the control input. In one embodiment, the control input is generated when the speed of the carrier relative to the rail exceeds a predetermined threshold.